Founder BRCA1 and BRCA2 mutations in French Canadian breast and ovarian cancer families

The journey from bench to bedside-it takes a science village

I was fortunate enough to start my career at what was the dawn of modern-day molecular biology and to apply it to an important health problem. While my early work focused on fundamental science, the desire to understand human disease better and to find practical applications for research discoveries resulted, over the following decades, in creating a stream of translational research directed specifically toward epithelial cancers. This could only have been possible through multiple collaborations. This type of team science would eventually become a hallmark of my career. With the development of higher throughput molecular techniques, the pace of research and discovery has quickened, and the concept of personalized medicine based on genomics is now coming to fruition. I hope my legacy will not just reflect my published works, but will also include the impact I have had on the development of the next generation of scientists and clinician scientists who inspired me with their dedication, knowledge, and enthusiasm.

Molecular Genetic Characteristics of FANCI, a Proposed New Ovarian Cancer Predisposing Gene

FANCI was recently identified as a new candidate ovarian cancer (OC)-predisposing gene from the genetic analysis of carriers of FANCI c.1813C>T; p.L605F in OC families. Here, we aimed to investigate the molecular genetic characteristics of FANCI, as they have not been described in the context of cancer. We first investigated the germline genetic landscape of two sisters with OC from the discovery FANCI c.1813C>T; p.L605F family (F1528) to re-affirm the plausibility of this candidate. As we did not find other conclusive candidates, we then performed a candidate gene approach to identify other candidate variants in genes involved in the FANCI protein interactome in OC families negative for pathogenic variants in BRCA1, BRCA2, BRIP1, RAD51C, RAD51D, and FANCI, which identified four candidate variants. We then investigated FANCI in high-grade serous ovarian carcinoma (HGSC) from FANCI c.1813C>T carriers and found evidence of loss of the wild-type allele in tumour DNA from some of these cases. The somatic genetic landscape of OC tumours from FANCI c.1813C>T carriers was investigated for mutations in selected genes, copy number alterations, and mutational signatures, which determined that the profiles of tumours from carriers were characteristic of features exhibited by HGSC cases. As other OC-predisposing genes such as BRCA1 and BRCA2 are known to increase the risk of other cancers including breast cancer, we investigated the carrier frequency of germline FANCI c.1813C>T in various cancer types and found overall more carriers among cancer cases compared to cancer-free controls (p = 0.007). In these different tumour types, we also identified a spectrum of somatic variants in FANCI that were not restricted to any specific region within the gene. Collectively, these findings expand on the characteristics described for OC cases carrying FANCI c.1813C>T; p.L605F and suggest the possible involvement of FANCI in other cancer types at the germline and/or somatic level.

Genetic analyses of DNA repair pathway associated genes implicate new candidate cancer predisposing genes in ancestrally defined ovarian cancer cases

Not all familial ovarian cancer (OC) cases are explained by pathogenic germline variants in known risk genes. A candidate gene approach involving DNA repair pathway genes was applied to identify rare recurring pathogenic variants in familial OC cases not associated with known OC risk genes from a population exhibiting genetic drift. Whole exome sequencing (WES) data of 15 OC cases from 13 families tested negative for pathogenic variants in known OC risk genes were investigated for candidate variants in 468 DNA repair pathway genes. Filtering and prioritization criteria were applied to WES data to select top candidates for further analyses. Candidates were genotyped in ancestry defined study groups of 214 familial and 998 sporadic OC or breast cancer (BC) cases and 1025 population-matched controls and screened for additional carriers in 605 population-matched OC cases. The candidate genes were also analyzed in WES data from 937 familial or sporadic OC cases of diverse ancestries. Top candidate variants in ERCC5, EXO1, FANCC, NEIL1 and NTHL1 were identified in 5/13 (39%) OC families. Collectively, candidate variants were identified in 7/435 (1.6%) sporadic OC cases and 1/566 (0.2%) sporadic BC cases versus 1/1025 (0.1%) controls. Additional carriers were identified in 6/605 (0.9%) OC cases. Tumour DNA from ERCC5, NEIL1 and NTHL1 variant carriers exhibited loss of the wild-type allele. Carriers of various candidate variants in these genes were identified in 31/937 (3.3%) OC cases of diverse ancestries versus 0-0.004% in cancer-free controls. The strategy of applying a candidate gene approach in a population exhibiting genetic drift identified new candidate OC predisposition variants in DNA repair pathway genes.

The Genetic and Molecular Analyses of RAD51C and RAD51D Identifies Rare Variants Implicated in Hereditary Ovarian Cancer from a Genetically Unique Population

To identify candidate variants in RAD51C and RAD51D ovarian cancer (OC) predisposing genes by investigating French Canadians (FC) exhibiting unique genetic architecture. Candidates were identified by whole exome sequencing analysis of 17 OC families and 53 early-onset OC cases. Carrier frequencies were determined by the genetic analysis of 100 OC or HBOC families, 438 sporadic OC cases and 1025 controls. Variants of unknown function were assayed for their biological impact and/or cellular sensitivity to olaparib. RAD51C c.414G>C;p.Leu138Phe and c.705G>T;p.Lys235Asn and RAD51D c.137C>G;p.Ser46Cys, c.620C>T;p.Ser207Leu and c.694C>T;p.Arg232Ter were identified in 17.6% of families and 11.3% of early-onset cases. The highest carrier frequency was observed in OC families (1/44, 2.3%) and sporadic cases (15/438, 3.4%) harbouring RAD51D c.620C>T versus controls (1/1025, 0.1%). Carriers of c.620C>T (n = 7), c.705G>T (n = 2) and c.137C>G (n = 1) were identified in another 538 FC OC cases. RAD51C c.705G>T affected splicing by skipping exon four, while RAD51D p.Ser46Cys affected protein stability and conferred olaparib sensitivity. Genetic and functional assays implicate RAD51C c.705G>T and RAD51D c.137C>G as likely pathogenic variants in OC. The high carrier frequency of RAD51D c.620C>T in FC OC cases validates previous findings. Our findings further support the role of RAD51C and RAD51D in hereditary OC.

Prevalence of specific and recurrent/founder pathogenic variants in BRCA genes in breast and ovarian cancer in North Africa

Background

Elucidation of specific and recurrent/founder pathogenic variants (PVs) in BRCA (BRCA1 and BRCA2) genes can make the genetic testing, for breast cancer (BC) and/or ovarian cancer (OC), affordable for developing nations.

Methods

To establish the knowledge about BRCA PVs and to determine the prevalence of the specific and recurrent/founder variants in BRCA genes in BC and/or OC women in North Africa, a systematic review was conducted in Morocco, Algeria, and Tunisia.

Results

Search of the databases yielded 25 relevant references, including eleven studies in Morocco, five in Algeria, and nine in Tunisia. Overall, 15 studies investigated both BRCA1 and BRCA2 genes, four studies examined the entire coding region of the BRCA1 gene, and six studies in which the analysis was limited to a few BRCA1 and/or BRCA2 exons. Overall, 76 PVs (44 in BRCA1 and32 in BRCA2) were identified in 196 BC and/or OC patients (129 BRCA1 and 67 BRCA2 carriers). Eighteen of the 76 (23.7%) PVs [10/44 (22.7%) in BRCA1 and 8/32 (25%) in BRCA2] were reported for the first time and considered to be novel PVs. Among those identified as unlikely to be of North African origin, the BRCA1 c.68_69del and BRCA1 c.5266dupC Jewish founder alleles and PVs that have been reported as recurrent/founder variants in European populations (ex: BRCA1 c.181T>G, BRCA1 c1016dupA). The most well characterized PVs are four in BRCA1 gene [c.211dupA (14.7%), c.798_799detTT (14%), c.5266dup (8.5%), c.5309G>T (7.8%), c.3279delC (4.7%)] and one in BRCA2 [c.1310_1313detAAGA (38.9%)]. The c.211dupA and c.5309G>T PVs were identified as specific founder variants in Tunisia and Morocco, accounting for 35.2% (19/54) and 20.4% (10/49) of total established BRCA1 PVs, respectively. c.798_799delTT variant was identified in 14% (18/129) of all BRCA1 North African carriers, suggesting a founder allele. A broad spectrum of recurrent variants including BRCA1 3279delC, BRCA1 c.5266dup and BRCA2 c.1310_1313detAAGA was detected in 42 patients. BRCA1 founder variants explain around 36.4% (47/129) of BC and outnumber BRCA2 founder variants by a ratio of ≈3:1.

Conclusions

Testing BC and/or OC patients for the panel of specific and recurrent/founder PVs might be the most cost-effective molecular diagnosis strategy.

A functionally impaired missense variant identified in French Canadian families implicates FANCI as a candidate ovarian cancer-predisposing gene

Background

Familial ovarian cancer (OC) cases not harbouring pathogenic variants in either of the BRCA1 and BRCA2 OC-predisposing genes, which function in homologous recombination (HR) of DNA, could involve pathogenic variants in other DNA repair pathway genes.

Methods

Whole exome sequencing was used to identify rare variants in HR genes in a BRCA1 and BRCA2 pathogenic variant negative OC family of French Canadian (FC) ancestry, a population exhibiting genetic drift. OC cases and cancer-free individuals from FC and non-FC populations were investigated for carrier frequency of FANCI c.1813C>T; p.L605F, the top-ranking candidate. Gene and protein expression were investigated in cancer cell lines and tissue microarrays, respectively.

Results

In FC subjects, c.1813C>T was more common in familial (7.1%, 3/42) than sporadic (1.6%, 7/439) OC cases (P = 0.048). Carriers were detected in 2.5% (74/2950) of cancer-free females though female/male carriers were more likely to have a first-degree relative with OC (121/5249, 2.3%; Spearman correlation = 0.037; P = 0.011), suggesting a role in risk. Many of the cancer-free females had host factors known to reduce risk to OC which could influence cancer risk in this population. There was an increased carrier frequency of FANCI c.1813C>T in BRCA1 and BRCA2 pathogenic variant negative OC families, when including the discovery family, compared to cancer-free females (3/23, 13%; OR = 5.8; 95%CI = 1.7–19; P = 0.005). In non-FC subjects, 10 candidate FANCI variants were identified in 4.1% (21/516) of Australian OC cases negative for pathogenic variants in BRCA1 and BRCA2, including 10 carriers of FANCI c.1813C>T. Candidate variants were significantly more common in familial OC than in sporadic OC (P = 0.04). Localization of FANCD2, part of the FANCI-FANCD2 (ID2) binding complex in the Fanconi anaemia (FA) pathway, to sites of induced DNA damage was severely impeded in cells expressing the p.L605F isoform. This isoform was expressed at a reduced level, destabilized by DNA damaging agent treatment in both HeLa and OC cell lines, and exhibited sensitivity to cisplatin but not to a poly (ADP-ribose) polymerase inhibitor. By tissue microarray analyses, FANCI protein was consistently expressed in fallopian tube epithelial cells and only expressed at low-to-moderate levels in 88% (83/94) of OC samples.

Conclusions

This is the first study to describe candidate OC variants in FANCI, a member of the ID2 complex of the FA DNA repair pathway. Our data suggest that pathogenic FANCI variants may modify OC risk in cancer families.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13073-021-00998-5.

Differences in Ovarian and Other Cancers Risks by Population and BRCA Mutation Location

Hereditary breast and ovarian cancer is caused by a germline mutation in BRCA1 or BRCA2 genes. The frequency of germline BRCA1/2 gene mutation carriers and the ratio of germline BRCA1 to BRCA2 mutations in BRCA-related cancer patients vary depending on the population. Genotype and phenotype correlations have been reported in BRCA mutant families, however, the correlations are rarely used for individual risk assessment and management. BRCA genetic testing has become a companion diagnostic for PARP inhibitors, and the number of families with germline BRCA mutation identified is growing rapidly. Therefore, it is expected that analysis of the risk of developing cancer will be possible in a large number of BRCA mutant carriers, and there is a possibility that personal and precision medicine for the carriers with specific common founder mutations will be realized. In this review, we investigated the association of ovarian cancer risk and BRCA mutation location, and differences of other BRCA-related cancer risks by BRCA1/2 mutation, and furthermore, we discussed the difference in the prevalence of germline BRCA mutation in ovarian cancer patients. As a result, although there are various discussions, there appear to be differences in ovarian cancer risk by population and BRCA mutation location. If it becomes possible to estimate the risk of developing BRCA-related cancer for each BRCA mutation type, the age at risk-reducing salpingo-oophorectomy can be determined individually. The decision would bring great benefits to young women with germline BRCA mutations.

The Genetic Analyses of French Canadians of Quebec Facilitate the Characterization of New Cancer Predisposing Genes Implicated in Hereditary Breast and/or Ovarian Cancer Syndrome Families

The French Canadian population of the province of Quebec has been recognized for its contribution to research in medical genetics, especially in defining the role of heritable pathogenic variants in cancer predisposing genes. Multiple carriers of a limited number of pathogenic variants in BRCA1 and BRCA2, the major risk genes for hereditary breast and/or ovarian cancer syndrome families, have been identified in French Canadians, which is in stark contrast to the array of over 2000 different pathogenic variants reported in each of these genes in other populations. As not all such cancer syndrome families are explained by BRCA1 and BRCA2, newly proposed gene candidates identified in other populations have been investigated for their role in conferring risk in French Canadian cancer families. For example, multiple carriers of distinct variants were identified in PALB2 and RAD51D. The unique genetic architecture of French Canadians has been attributed to shared ancestry due to common ancestors of early settlers of this population with origins mainly from France. In this review, we discuss the merits of genetically characterizing cancer predisposing genes in French Canadians of Quebec. We focused on genes that have been implicated in hereditary breast and/or ovarian cancer syndrome families as they have been the most thoroughly characterized cancer syndromes in this population. We describe how genetic analyses of French Canadians have facilitated: (i) the classification of variants in BRCA1 and BRCA2; (ii) the identification and classification of variants in newly proposed breast and/or ovarian cancer predisposing genes; and (iii) the identification of a new breast cancer predisposing gene candidate, RECQL. The genetic architecture of French Canadians provides a unique opportunity to evaluate new candidate cancer predisposing genes regardless of the population in which they were identified.

Investigating the causal role of MRE11A p.E506* in breast and ovarian cancer

The nuclease MRE11A is often included in genetic test panels for hereditary breast and ovarian cancer (HBOC) due to its BRCA1-related molecular function in the DNA repair pathway. However, whether MRE11A is a true predisposition gene for HBOC is still questionable. We determined to investigate this notion by dissecting the molecular genetics of the c.1516G > T;p.E506* truncating MRE11A variant, that we pinpointed in two unrelated French-Canadian (FC) HBOC patients. We performed a case–control study for the variant in ~ 2500 breast, ovarian, and endometrial cancer patients from the founder FC population of Quebec. Furthermore, we looked for the presence of second somatic alterations in the MRE11A gene in the tumors of the carriers. In summary, these investigations suggested that the identified variant is not associated with an increased risk of developing breast or ovarian cancer. We finally performed a systematic review for all the previously reported MRE11A variants in breast and ovarian cancer. We found that MRE11A germline variants annotated as pathogenic on ClinVar often lacked evidence for such classification, hence misleading the clinical management for affected patients. In summary, our report suggests the lack of clinical utility of MRE11A testing in HBOC, at least in the White/Caucasian populations.

Literature Review of BARD1 as a Cancer Predisposing Gene with a Focus on Breast and Ovarian Cancers

Soon after the discovery of BRCA1 and BRCA2 over 20 years ago, it became apparent that not all hereditary breast and/or ovarian cancer syndrome families were explained by germline variants in these cancer predisposing genes, suggesting that other such genes have yet to be discovered. BRCA1-associated ring domain (BARD1), a direct interacting partner of BRCA1, was one of the earliest candidates investigated. Sequencing analyses revealed that potentially pathogenic BARD1 variants likely conferred a low-moderate risk to hereditary breast cancer, but this association is inconsistent. Here, we review studies of BARD1 as a cancer predisposing gene and illustrate the challenge of discovering additional cancer risk genes for hereditary breast and/or ovarian cancer. We selected peer reviewed research articles that focused on three themes: (i) sequence analyses of BARD1 to identify potentially pathogenic germline variants in adult hereditary cancer syndromes; (ii) biological assays of BARD1 variants to assess their effect on protein function; and (iii) association studies of BARD1 variants in family-based and case-control study groups to assess cancer risk. In conclusion, BARD1 is likely to be a low-moderate penetrance breast cancer risk gene.

Founder BRCA1/BRCA2/PALB2 pathogenic variants in French-Canadian breast cancer cases and controls

Inherited germline pathogenic variants are responsible for ~5% of breast cancer globally. Through rapid expansion and isolation since immigration in the early 17th century, French Canadians are a relatively genetically homogenous founder population and therefore represent a unique demographic for genetic contributions to disease. To date, twenty variants in BRCA1, BRCA2, and PALB2 that predispose families to breast and ovarian cancer have been identified as recurring in the French-Canadian founder population. Our objective was to evaluate the clinical efficacy and validity of targeted genetic testing for these variants in Montreal French Canadians. A total of 555 breast cancer cases unselected for family history or age of diagnosis were genotyped, along with 1940 controls without a personal or family history of cancer. A Sequenom genotyping assay identified a pathogenic variant in 0.2% (5 of 1940) of cancer-free controls, and 3.8% (21/555) of breast cancer cases. Almost 10% (12/113) of early onset cases were heterozygous for founder BRCA1 or BRCA2 pathogenic variant. Of twenty variants tested, only seven were identified in this study. The option of providing this test as population-based screening is discussed.

Mutations in context: implications of BRCA testing in diverse populations

Cancer is a common non-communicable disease worldwide, although it exhibits differential population trends in incidence and mortality rates. The differences relate to population structure, environmental risk factors as well as health system organization. This article discusses the potential impact of genetic testing on population health, focusing in particular on the mutational spectrum of breast cancer susceptibility genes in diverse populations. We identify the need for improved access to, and increased investment in, comprehensive cancer risk assessment and genetic testing as well as cancer control measures that take into account lifestyle, environmental, and social factors in understudied minority groups.

A new bioinformatics tool to help assess the significance of BRCA1 variants

Background

Germline pathogenic variants in the breast cancer type 1 susceptibility gene BRCA1 are associated with a 60% lifetime risk for breast and ovarian cancer. This overall risk estimate is for all BRCA1 variants; obviously, not all variants confer the same risk of developing a disease. In cancer patients, loss of BRCA1 function in tumor tissue has been associated with an increased sensitivity to platinum agents and to poly-(ADP-ribose) polymerase (PARP) inhibitors. For clinical management of both at-risk individuals and cancer patients, it would be important that each identified genetic variant be associated with clinical significance. Unfortunately for the vast majority of variants, the clinical impact is unknown. The availability of results from studies assessing the impact of variants on protein function may provide insight of crucial importance.

Results and conclusion

We have collected, curated, and structured the molecular and cellular phenotypic impact of 3654 distinct BRCA1 variants. The data was modeled in triple format, using the variant as a subject, the studied function as the object, and a predicate describing the relation between the two. Each annotation is supported by a fully traceable evidence. The data was captured using standard ontologies to ensure consistency, and enhance searchability and interoperability. We have assessed the extent to which functional defects at the molecular and cellular levels correlate with the clinical interpretation of variants by ClinVar submitters. Approximately 30% of the ClinVar BRCA1 missense variants have some molecular or cellular assay available in the literature. Pathogenic variants (as assigned by ClinVar) have at least some significant functional defect in 94% of testable cases. For benign variants, 77% of ClinVar benign variants, for which neXtProt Cancer variant portal has data, shows either no or mild experimental functional defects. While this does not provide evidence for clinical interpretation of variants, it may provide some guidance for variants of unknown significance, in the absence of more reliable data.

The neXtProt Cancer variant portal (https://www.nextprot.org/portals/breast-cancer) contains over 6300 observations at the molecular and/or cellular level for BRCA1 variants.

A comprehensive analysis of BRCA2 gene: focus on mechanistic aspects of its functions, spectrum of deleterious mutations, and therapeutic strategies targeting BRCA2-deficient tumors

BRCA2is the main susceptibility gene known to be involved in the pathogenesis of breast cancer. It plays an important role in maintaining the genome stability by homologous recombination through DNA double-strand breaks repairing, by interacting with various other proteins including RAD51, DSS1, RPA, MRE11, PALB2, and p53. BRCA2-deficient cells show the abnormalities of chromosome number. BRCA2 is also found to be involved in centrosome duplication specifically in the metaphase to anaphase transition. Inactivation or depletion of BRCA2 leads to centrosome amplification that results in unequal separation of chromosomes. BRCA2 localizes with central spindle and midbody during telophase and cytokinesis. Inactivation or depletion of BRCA2 leads to multinucleation of cell. Around 2000 mutations have been reported in BRCA2 gene. BRCA2-deficient tumors are being taking into consideration for targeted cancer therapy by using different inhibitors like poly ADP-ribose polymerase and thymidylate synthase. The present review focusses on the role of BRCA2 in various critical cellular processes based on the mechanistic approaches. Mutations reported in the BRCA2 gene in various ethnic groups till date have also been compiled with an insight into the functional aspects of these alterations. The therapeutic strategies for targeting BRCA2-deficient tumors have also been targeted.

Impact of germline and somatic BRCA1/2 mutations: tumor spectrum and detection platforms

The BRCA1/2 genes are long and complex and mutation carriers are at risk of developing malignancies, mainly of gynecological origin. Various mutations arise in these genes and their characterization is a time-consuming, cost intensive, complicated process. Tumors of BRCA1/2 origin have distinct molecular and histological features that can impact responses to therapy. Therefore, detection of these mutations constitutes an important step in the risk assessment, prevention strategy and treatment of subjects. Although Sanger sequencing is the gold standard for the detection of genetic mutations, several next generation sequencing-based high throughput platforms have been developed and adapted for the detection of BRCA1/2 mutations. This review provides a comprehensive overview of the sequencing platforms available for the screening and identification of these mutations. We also summarize what is known about the different types of mutations that arise in these genes and the tumor spectra they result in. Finally, we present a short discussion on existing clinical guidelines which assist physicians in the decision-making process. These parameters have important consequences for the management of patients and an urgent need exists for the development of detection platforms that are cost effective and can provide clinicians with conclusive results within a significantly shorter time.

Pedigree and BRCA gene analysis in breast cancer patients to identify hereditary breast and ovarian cancer syndrome to prevent morbidity and mortality of disease in Indian population

Global burden of breast cancer is expected to increase to >2 million new cases every year by 2030 and 10% of these are likely to have hereditary breast and ovarian cancer syndrome. Identifying these individuals by pedigree and BRCA1/2 mutation analyses will enable us to offer targeted mutation testing and appropriate counseling. This study from a tertiary care hospital showed that of the 127 breast cancer patients on treatment during 2014-2015, 24 of them fulfilled the criteria of hereditary breast and ovarian cancer syndrome after detailed verbal autopsy and pedigree analysis, and BRCA1 and 2 next-generation sequencing done after pre-test counseling revealed mutations in 13 cases (54%), these included 9 BRCA1 mutations (69%) and 4 BRCA2 mutation (31%). Subsequent post-test counseling recommended targeted mutation analysis for 64 high-risk members in these 13 families with pathogenic mutations, which will help in surveillance for early detection, appropriate management, and prevention of the disease by decreasing the burden to both family and nation. Results from this preliminary study highlight the importance of genetic counseling, pedigree analysis, and genetic testing. It can be recommended that all oncology units should have a genetic counseling service for providing appropriate support to oncologists, patients, and families to prevent unnecessary testing; however, breast cancer screening program is incomplete without evaluating for hereditary breast and ovarian cancer syndrome.

A curated gene list for reporting results of newborn genomic sequencing

PURPOSE

Genomic sequencing (GS) for newborns may enable detection of conditions for which early knowledge can improve health outcomes. One of the major challenges hindering its broader application is the time it takes to assess the clinical relevance of detected variants and the genes they impact so that disease risk is reported appropriately.

METHODS

To facilitate rapid interpretation of GS results in newborns, we curated a catalog of genes with putative pediatric relevance for their validity based on the ClinGen clinical validity classification framework criteria, age of onset, penetrance, and mode of inheritance through systematic evaluation of published evidence. Based on these attributes, we classified genes to guide the return of results in the BabySeq Project, a randomized, controlled trial exploring the use of newborn GS (nGS), and used our curated list for the first 15 newborns sequenced in this project.

RESULTS

Here, we present our curated list for 1,514 gene-disease associations. Overall, 954 genes met our criteria for return in nGS. This reference list eliminated manual assessment for 41% of rare variants identified in 15 newborns.

CONCLUSION

Our list provides a resource that can assist in guiding the interpretive scope of clinical GS for newborns and potentially other populations.Genet Med advance online publication 12 January 2017.

First case report of an adrenocortical carcinoma caused by a BRCA2 mutation

BACKGROUND

Adrenocortical carcinoma (ACC) may rarely be a component of inherited cancer syndromes such as Li-Fraumeni syndrome and Beckwith-Wiedemann syndrome. ACC caused by a BRCA2 mutation has never been reported.

METHODS

Nucleotide sequencing of BRCA2 in lymphocyte and tumoral DNA of a 50-year-old male who presented with an androgen-secreting ACC and a strong family history of breast, ovarian, and pancreatic cancers.

RESULTS

A germline BRCA2 2 bp heterozygous deletion at nucleotide 8765 (8765delAG) leading to a frameshift mutation (p.Glu2846GlyfsX23) was detected. Only the BRCA2 deleted allele was retained in the ACC tumoral DNA compared with the control DNA supporting a loss of heterozygosity in the tumor.

CONCLUSION

This is the first reported case of a patient with ACC associated with a BRCA2 germline mutation. Loss of heterozygosity in ACC DNA suggests a causal link with the BRCA2 8765delAG mutation.

The Genetics of Breast Cancer: What the Surgical Oncologist Needs to Know

This article summarizes the impact of germline predisposition to breast cancer on the surgical management of breast cancer and breast cancer risk. Surgical implications of germline predisposition to breast cancer are now more nuanced due to the application of increasingly more complicated next-generation sequencing-based tests. The rapid pace of change will continue to challenge paradigms for genetic cancer risk assessment, which can influence the medical and surgical management of breast cancer risk as well as strategies for screening and for risk reduction.

Family history predictors of BRCA1/BRCA2 mutation status among Tunisian breast/ovarian cancer families

BACKGROUND

With the increasing request for BRCA1/BRCA2 mutation tests, several risk models have been developed to predict the presence of mutation in these genes; in this study, we have developed an efficient BRCA genetic testing strategy.

METHOD

As first step, to identify predictor variables associated with BRCA status, we have undertaken a cumulative mutation analysis including data from three Tunisian studies. Then, we have developed a logistic regression model for predicting the likelihood of harboring a BRCA mutation. Using receiver operating characteristic curves (ROC), an effective evaluation was performed. A total of 92 Tunisian families were included. Overall, 27 women were positive for BRCA1/BRCA2 deleterious mutations.

RESULTS

Tow recurrent mutations (c.211dupA and c.5266dupC) explained 76 % of BRCA1-related families and three recurrent mutations (c.1310_1313del, c.1542_1547delAAGA and c.7887_7888insA) explained 90 % of BRCA2-related families. Early age at diagnosis of breast cancer, ovarian cancer, bilateral breast cancer were associated with BRCA1, whereas male breast cancer and four or more breast cancer cases in the family were associated with BRCA2. The area under the receiver operating characteristic curve of the risk score was 0.802 (95 % confidence interval = 0.0699-0. 905).

CONCLUSION

Logistic regression reported particular profiles related to BRCA germline mutation carriers in our population, as well as an efficient prediction model that may be a useful tool for increasing the cost-effectiveness of genetic testing strategy.

Genetic evaluation and testing for hereditary forms of cancer in the era of next-generation sequencing

The introduction of next-generation sequencing (NGS) technology in testing for hereditary cancer susceptibility allows testing of multiple cancer susceptibility genes simultaneously. While there are many potential benefits to utilizing this technology in the hereditary cancer clinic, including efficiency of time and cost, there are also important limitations that must be considered. The best panel for the given clinical situation should be selected to minimize the number of variants of unknown significance. The inclusion in panels of low penetrance or newly identified genes without specific actionability can be problematic for interpretation. Genetic counselors are an essential part of the hereditary cancer risk assessment team, helping the medical team select the most appropriate test and interpret the often complex results. Genetic counselors obtain an extended family history, counsel patients on the available tests and the potential implications of results for themselves and their family members (pre-test counseling), explain to patients the implications of the test results (post-test counseling), and assist in testing family members at risk.

Novel high-grade serous epithelial ovarian cancer cell lines that reflect the molecular diversity of both the sporadic and hereditary disease

Few cell line models of epithelial ovarian cancer (EOC) have been developed for the high-grade serous (HGS) subtype, which is the most common and lethal form of gynaecological cancer. Here we describe the establishment of six new EOC cell lines spontaneously derived from HGS tumors (TOV2978G, TOV3041G and TOV3291G) or ascites (OV866(2), OV4453 and OV4485). Exome sequencing revealed somatic TP53 mutations in five of the cell lines. One cell line has a novel BRCA1 splice-site mutation, and another, a recurrent BRCA2 nonsense mutation, both of germline origin. The novel BRCA1 mutation induced abnormal splicing, mRNA instability, resulting in the absence of BRCA1 protein. None of the cell lines harbor mutations in KRAS or BRAF, which are characteristic of other EOC subtypes. SNP arrays showed that all of the cell lines exhibited structural chromosomal abnormalities, copy number alterations and regions of loss of heterozygosity, consistent with those described for HGS. Four cell lines were able to produce 3D-spheroids, two exhibited anchorage-independent growth, and three (including the BRCA1 and BRCA2 mutated cell lines) formed tumors in SCID mice. These novel HGS EOC cell lines and their detailed characterization provide new research tools for investigating the most common and lethal form of EOC.

Germline RECQL mutations are associated with breast cancer susceptibility

Several moderate- and high-risk breast cancer susceptibility genes have been discovered, but more are likely to exist. To discover new breast cancer susceptibility genes, we used 2 populations (from Poland and Quebec, Canada) and applied whole-exome sequencing in a discovery phase (n = 195), followed by validation. We identified rare recurrent RECQL mutations in each population. In Quebec, 7 of 1,013 higher-risk breast cancer cases and 1 of 7,136 newborns carried the c.634C>T (p.Arg215*) variant (P = 0.00004). In Poland, 30 of 13,136 unselected breast cancer cases and 2 of 4,702 controls carried the c.1667_1667+3delAGTA (p.K555delinsMYKLIHYSFR) variant (P = 0.008). RECQL is implicated in resolving stalled DNA replication forks to prevent double-stranded DNA (dsDNA) breaks. This function is related to that of other known breast cancer susceptibility genes, many of which are involved in repairing dsDNA breaks. We conclude that RECQL is a breast cancer susceptibility gene.

Double PALB2 and BRCA1/BRCA2 mutation carriers are rare in breast cancer and breast-ovarian cancer syndrome families from the French Canadian founder population

French Canadian families with breast cancer and breast-ovarian cancer syndrome harbor specific BRCA1, BRCA2 and PALB2 germline mutations, which have been attributed to common founders. Mutations in these genes confer an increased risk to breast and ovarian cancers, and have been identified to play a role in and directly interact with the common homologous recombination DNA repair pathways. Our previous study described the case of a female diagnosed with breast cancer at 45 years old, who harbored the PALB2:c.2323C>T [p.Q775X] and BRCA2:c.9004G>A [p.E3002K] germline mutations, which have been found to recur in the French Canadian cancer families. As the frequency of double heterozygous carriers of breast-ovarian cancer susceptibility alleles is unknown, and due to the possibility that there may be implications for genetic counseling and management for these carriers, the present study investigated the co-occurrence of BRCA1/BRCA2 and PALB2 mutations in the French Canadian cancer families. The PALB2:c.2323C>T [p.Q775X] mutation, which is the only PALB2 mutation to have been identified in French Canadian cancer families, was screened in 214 breast cancer cases and 22 breast-ovarian cancer cases from 114 BRCA1/BRCA2 mutation-positive French Canadian breast cancer (n=61) and breast-ovarian cancer (n=53) families using a tailored polymerase chain reaction-based TaqMan® SNP Genotyping Assay. No additional PALB2:c.2323C>T [p.Q775X] mutation carriers were identified among the BRCA1/BRCA2 mutation carriers. The results suggest that carriers of the PALB2:c.2323C>T [p.Q775X] mutation rarely co-occur in French Canadian breast cancer and breast-ovarian cancer families harboring BRCA1 or BRCA2 mutations.

Germline TP53 mutational spectrum in French Canadians with breast cancer

BACKGROUND

Specific germline mutations in the hereditary breast-ovarian cancer susceptibility (HBC/HBOC) genes, BRCA1, BRCA2 and PALB2, have been shown to recur in French Canadians of Quebec, Canada, and this has been attributed to common ancestors. Germline TP53 mutation carriers are known to segregate in Li-Fraumeni syndrome families, which feature young age of onset breast cancer. We have reported rare TP53 mutation carriers in French Canadian HBC families, though none recurred possibly due to the limited number of cancer families investigated. Here we describe TP53 germline mutations found in French Canadian cancer families provided from hereditary cancer clinics; investigate 37 new BRCA1 and BRCA2 mutation-negative HBC/HBOC families for the TP53 mutations; and assess the frequency of TP53 mutations in a 1235 French Canadian breast cancer cases not selected for family history of cancer.

METHODS

TP53 mutation-positive pedigrees from French Canadian cancer families were provided from local hereditary cancer clinics. Bidirectional Sanger sequencing of all protein encoding exons of TP53 was performed using peripheral blood lymphocyte DNA from breast/ovarian cancer probands from 37 HBC/HBOC families of French Canadian descent. Targeted bidirectional Sanger sequencing assay of regions containing the identified TP53 mutations was performed on 1235 French Canadian breast cancer cases not selected for family history cancer.

RESULTS

Five new TP53 mutations were identified in six pedigrees from hereditary cancer clinics. No deleterious mutations were identified in cancer probands from 37 HBC/HBOC families. A targeted mutation screen of the 1235 breast cancer cases identified a c.844C>T [p.Arg282Trp] mutation carrier. This mutation was also found among the six mutation-positive cancer families provided by the local hereditary cancer clinics. The targeted screen also uncovered a new TP53 mutation, c.685T>C [p.Cys229Arg] that was found in two breast cancer cases. All TP53 mutation carriers were among the 656 women with breast cancer diagnosed less than 50 years of age.

CONCLUSIONS

In all six new TP53 mutations were identified in French Canadians, where two each occurred in independently ascertained cases/families. Although all newly identified breast cancer mutation carriers reported a family history of cancer, none were consistent with features of Li-Fraumeni syndrome families.

A targeted analysis identifies a high frequency of BRCA1 and BRCA2 mutation carriers in women with ovarian cancer from a founder population

Background

The frequency of BRCA1 and BRCA2 mutations in ovarian cancer patients varies depending on histological subtype and population investigated. The six most commonly recurring BRCA1 and BRCA2 mutations previously identified in a founder French Canadian population were investigated in 439 histologically defined ovarian, fallopian tube and primary peritoneal cancer cases that were ascertained at one hospital servicing French Canadians. To further assess the frequency of BRCA1/BRCA2 mutations, a defined subgroup of 116 cases were investigated for all mutations previously reported in this population.

Methods

A PCR-based assay was used to screen 439 ovarian, fallopian tube or extra-ovarian cancers comprised of serous, high grade endometrioid and mixed cell adenocarcinomas with serous components for specific BRCA1: C4446T and 2953delGTAinsC and BRCA2: 8765delAG, G6085T, 3398del5 and E3002K mutations. A multiplex bead-array-based Luminex assay was used to evaluate 19 specific mutations that have ever been reported in French Canadians, which included the six mutations assayed by PCR, in 116 cases representing all women ascertained within a defined 3-year window.

Results

A targeted analysis of six mutations identified 34/439 (7.7%) mutation carriers and at least two mutation carriers for each mutation screened were found. The BRCA1:C4446T mutation was the most frequently identified variant (15/34, 44.1%) among mutation-positive cases. The expanded mutation screen that also included 13 additional variants identified 19/116 (16.4%) mutation carriers, where C4446T was the most common variant (8/19, 42.1%) identified among mutation-positive carriers in this subgroup. Mutations were identified in women with serous, endometrioid, mixed cell, and undifferentiated adenocarcinomas. Within this subgroup there were 73 high-grade (G3) serous ovarian carcinomas, the most common subtype, with mutations identified in 19.2% (n = 14) serous cases.

Conclusions

Our results reaffirm that specific BRCA1 and BRCA2 mutations found previously to recur in French Canadian breast cancer and breast-ovarian cancer families, also recur in women with ovarian cancer not selected for family history of cancer. The high frequency of mutation carriers rationalizes genetic testing of ovarian cancer patients in this demographically defined population.

Electronic supplementary material

The online version of this article (doi:10.1186/s13048-015-0124-8) contains supplementary material, which is available to authorized users.

Multiple primary cancers as a guide to heritability

There are approximately 100 genes which when mutated are known to predispose to one or more forms of cancer. Currently, genetic testing is offered for many of these, either as single genes or as multi-gene panels. Features of hereditary cancer include a positive family history of cancer, early age of onset and the appearance of multiple primary cancers in one individual. In some cases multiple cancers may be of the same site (e.g., bilateral breast cancer) and in other cases they may be at different sites. Various combinations of cancer sites may be indicative of specific cancer syndromes such as the breast ovarian cancer syndrome. Genetic testing should be offered to individuals who have experienced multiple primary cancers in some circumstances, the genetic counselor should review the ages of sites of cancer, their pathologic features and the family history of cancer as part of the pre-test evaluation.

Hereditary breast and ovarian cancer: assessment of point mutations and copy number variations in Brazilian patients

BACKGROUND

Germ line mutations in BRCA1 and BRCA2 (BRCA1/2) and other susceptibility genes have been identified as genetic causes of hereditary breast and ovarian cancer (HBOC). To identify the disease-causing mutations in a cohort of 120 Brazilian women fulfilling criteria for HBOC, we carried out a comprehensive screening of BRCA1/2, TP53 R337H, CHEK2 1100delC, followed by an analysis of copy number variations in 14 additional breast cancer susceptibility genes (PTEN, ATM, NBN, RAD50, RAD51, BRIP1, PALB2, MLH1, MSH2, MSH6, TP53, CDKN2A, CDH1 and CTNNB1).

METHODS

Capillary sequencing and multiplex ligation-dependent probe amplification (MLPA) were used for detecting point mutations and copy number variations (CNVs), respectively, for the BRCA1 and BRCA2 genes; capillary sequencing was used for point mutation for both variants TP53 R337H and CHEK2 1100delC, and finally array comparative genomic hybridization (array-CGH) was used for identifying CNVs in the 14 additional genes.

RESULTS

The positive detection rate in our series was 26%. BRCA1 pathogenic mutations were found in 20 cases, including two cases with CNVs, whereas BRCA2 mutations were found in 7 cases. We also found three patients with the TP53 R337H mutation and one patient with the CHEK2 1100delC mutation. Seven (25%) pathogenic mutations in BRCA1/2 were firstly described, including a splice-site BRCA1 mutation for which pathogenicity was confirmed by the presence of an aberrant transcript showing the loss of the last 62 bp of exon 7. Microdeletions of exon 4 in ATM and exon 2 in PTEN were identified in BRCA2-mutated and BRCA1/2-negative patients, respectively.

CONCLUSIONS

In summary, our results showed a high frequency of BRCA1/2 mutations and a higher prevalence of BRCA1 (64.5%) gene. Moreover, the detection of the TP53 R337H variant in our series and the fact that this variant has a founder effect in our population prompted us to suggest that all female breast cancer patients with clinical criteria for HBOC and negative for BRCA1/2 genes should be tested for the TP53 R337H variant. Furthermore, the presence of genomic structural rearrangement resulting in CNVs in other genes that predispose breast cancer in conjunction with BRCA2 point mutations demonstrated a highly complex genetic etiology in Brazilian breast cancer families.

Cultural aspects of healthy BRCA carriers from two ethnocultural groups

We explored the experiences of Ashkenazi Jewish and French Canadian women and meanings attributed to their hereditary breast and ovarian cancer (HBOC) risk. We purposively sampled 40 BRCA1 or BRCA2 (BRCA) mutation carriers and conducted theoretically driven semistructured interviews. According to content analysis, participants from these two ethnocultural groups held divergent meanings associated with being a BRCA carrier and different views pertaining to the illness experience and risk awareness. All participants identified a genetic basis; however, the French Canadian women also expressed other causes. The French Canadian women reported not knowing other carriers in their social environment, whereas the Ashkenazi Jewish women emphasized a strong sense of community contributing to their ethnic risk awareness. Based on these findings, we suggest that French Canadian women could benefit from greater awareness of the HBOC genetic risk and that health care providers should consider ethnically related and individual-based experiences and meanings during counseling.

Prevalence of BRCA1 and BRCA2 mutations in unselected breast cancer patients from medellín, Colombia

BACKGROUND

Approximately 5% of all breast cancers can be attributed to a mutation in the BRCA1 or BRCA2 gene. The genetic component of breast cancer in Colombia has been, for the most part, studied on cases from the Bogota region. Five different founder mutations were in two studies of breast cancer patients in the Bogota region. It is important that the frequency of mutations be established among unselected cases of breast cancer of other regions of Colombia in order to estimate the genetic burden of this cancer in Colombia and to plan genetic services. The aim of this study was to establish the mutation frequencies of the BRCA genes in breast cancer patients unselected for family history or age, from Medellin, Colombia.

METHODS

We enrolled 280 unselected women with breast cancer from a large public hospital in Medellin, Colombia. A detailed family history from each patient and a blood sample was obtained and processed for DNA analysis. Mutations in BRCA1 and BRCA2 were sought using a combination of techniques including a panel of recurrent Hispanic BRCA mutations which consists of fifty BRCA1 mutations and forty-six BRCA2 mutations, including the five recurrent Colombian BRCA mutations. All mutations were confirmed by direct sequencing.

RESULTS

Genetic testing was successfully completed for 244 of the 280 cases (87%). Among the 244 cases, three deleterious mutations were identified (two in BRCA1 and one in BRCA2) representing 1.2% of the total. The average age of breast cancer in the mutation-positive cases was 34 years. The two BRCA1 mutations were known founder mutations (3450del4 in exon 11 and A1708E in exon 18). The BRCA2 mutation was in exon 11 (5844del5) and has not been previously reported in individuals of Colombian descent. Among the three mutation-positive families was a breast cancer family and two families with no history of breast or ovarian cancer.

CONCLUSION

The frequency of BRCA mutations in unselected breast cancer cases from the Medellin region of Colombia is low and is approximately 1.2%.

Recurrent mutations of BRCA1 and BRCA2 in Poland: an update

Three founder alleles of BRCA1 (C61G, 4153delA, 5382insC) were reported in Poland in 2000, and these three mutations have comprised the standard testing panel used throughout the country. However, since 2000, other recurrent mutations of BRCA1 and BRCA2 have been reported. To establish if the inclusion of one or more of these mutations will increase the sensitivity of the standard test panel, we studied 1164 Polish women with unselected breast cancer diagnosed at age of 50 or below. All women were genotyped for 12 recurrent mutations of BRCA1 and BRCA2. We identified a mutation in 83 of 1164 patients (7.1%) including 61 women with one of the original three mutations (C61G, 4153delA, 5382insC) and 22 women with a different mutation (1.9%). Three new mutations (3819del5, 185delAG and 5370C>T) were seen in multiple families. By including these three mutations in the extended panel, the mutant frequency increased from 5.2 to 6.7%. Polish women with breast cancer diagnosed at age of 50 or below should be screened with a panel of six founder mutations of BRCA1 (C61G, 4153delA, 5382insC, 3819del5, 185delAG and 5370C>T).

Familial prostate cancer: the damage done and lessons learnt

BACKGROUND

A 51-year-old French Canadian man presented to his family physician owing to an extensive family history of prostate cancer in five brothers, his father and two paternal uncles. His serum PSA level was 4.9 ng/ml and a six-core biopsy revealed the presence of a prostate adenocarcinoma with a Gleason score of 7 (3+4). He was treated with radical prostatectomy. Repeat PSA tests revealed a gradual rise in PSA levels despite androgen deprivation therapy with bicalutamide and goserelin over the course of 3 years. Genetic evaluation was undertaken in view of his personal and family history. The proband died at the age of 58 years of widespread metastasis.

INVESTIGATIONS

PSA testing, six-core biopsy, genetic counselling and mutation analysis for French Canadian founder mutations in the BRCA1 and BRCA2 genes, histopathological review of tumour tissue from family members, examination of loss of heterozygosity at the BRCA2 gene locus, immunohistochemistry to determine the expression of the ERG nuclear oncoprotein in prostate tumours, genotyping with eight selected risk-associated single nucleotide polymorphisms, Doppler ultrasonography of the leg, CT of the abdomen and pelvis with intravenous and oral contrast, chest CT with intravenous contrast for the assessment of metastatic prostate cancer, genetic testing for the G84E variant in the HOXB13 gene.

DIAGNOSIS

Early-onset and aggressive prostate cancer associated with a nonsense French Canadian BRCA2 founder mutation, c.5857G>T (p.Glu1953(*)).

MANAGEMENT

Radical prostatectomy, hormone therapy with bicalutamide and goserelin, palliative chemotherapy initially with docetaxel plus prednisone then with mitoxantrone plus prednisone, as well as genetic counselling and testing for the proband and his family members.

Contribution of the PALB2 c.2323C>T [p.Q775X] founder mutation in well-defined breast and/or ovarian cancer families and unselected ovarian cancer cases of French Canadian descent

BACKGROUND

The PALB2 c.2323C>T [p.Q775X] mutation has been reported in at least three breast cancer families and breast cancer cases of French Canadian descent and this has been attributed to common ancestors. The number of mutation-positive cases reported varied based on criteria of ascertainment of index cases tested. Although inherited PALB2 mutations are associated with increased risks of developing breast cancer, risk to ovarian cancer has not been fully explored in this demographically unique population.

METHODS

We screened the PALB2 p.Q775X variant in 71 families with at least three cases of breast cancer (n=48) or breast and ovarian cancers (n=23) that have previously been found negative for at least the most common BRCA1 and BRCA2 mutations reported in the French Canadian population and in 491 women of French Canadian descent who had invasive ovarian cancer and/or low malignant potential tumors of the major histopathological subtypes.

RESULTS

We identified a PALB2 p.Q775X carrier in a breast cancer family, who had invasive ductal breast carcinomas at 39 and 42 years of age. We also identified a PALB2 p.Q775X carrier who had papillary serous ovarian cystadenocarcinoma at age 58 among the 238 serous subtype ovarian cancer cases investigated, who also had breast cancer at age 52.

CONCLUSION

Our findings, taken together with previous reports, support adding PALB2 c.2323C>T p.Q775X to the list of cancer susceptibility genes for which founder mutations have been identified in the French Canadian population.

Prevalence and type of BRCA mutations in Hispanics undergoing genetic cancer risk assessment in the southwestern United States: a report from the Clinical Cancer Genetics Community Research Network

PURPOSE

To determine the prevalence and type of BRCA1 and BRCA2 (BRCA) mutations among Hispanics in the Southwestern United States and their potential impact on genetic cancer risk assessment (GCRA).

PATIENTS AND METHODS

Hispanics (n = 746) with a personal or family history of breast and/or ovarian cancer were enrolled in an institutional review board-approved registry and received GCRA and BRCA testing within a consortium of 14 clinics. Population-based Hispanic breast cancer cases (n = 492) enrolled in the Northern California Breast Cancer Family Registry, negative by sequencing for BRCA mutations, were analyzed for the presence of the BRCA1 ex9-12del large rearrangement.

RESULTS

Deleterious BRCA mutations were detected in 189 (25%) of 746 familial clinic patients (124 BRCA1, 65 BRCA2); 21 (11%) of 189 were large rearrangement mutations, of which 62% (13 of 21) were BRCA1 ex9-12del. Nine recurrent mutations accounted for 53% of the total. Among these, BRCA1 ex9-12del seems to be a Mexican founder mutation and represents 10% to 12% of all BRCA1 mutations in clinic- and population-based cohorts in the United States.

CONCLUSION

BRCA mutations were prevalent in the largest study of Hispanic breast and/or ovarian cancer families in the United States to date, and a significant proportion were large rearrangement mutations. The high frequency of large rearrangement mutations warrants screening in every case. We document the first Mexican founder mutation (BRCA1 ex9-12del), which, along with other recurrent mutations, suggests the potential for a cost-effective panel approach to ancestry-informed GCRA.

NSGC practice guideline: risk assessment and genetic counseling for hereditary breast and ovarian cancer

PURPOSE

The purpose of this document is to present a current and comprehensive set of practice recommendations for effective genetic cancer risk assessment, counseling and testing for hereditary breast and ovarian cancer. The intended audience is genetic counselors and other health professionals who care for individuals with, or at increased risk of, hereditary breast and/or ovarian cancer.

Identification of the prevalent BRCA1 and BRCA2 mutations in the female population of Puerto Rico

Mutations in the breast cancer 1, early onset (BRCA1) and breast cancer 2 (BRCA2) genes are responsible for the majority of hereditary breast cancers. Knowledge of the incidence and prevalence of BRCA mutations in a specific population or ethnic group is necessary to provide accurate genetic counseling for breast cancer patients and their families; however, these data have not been gathered in the population of Puerto Rico. We conducted a retrospective study of female breast cancer patients undergoing genetic testing for BRCA mutations in the highest-volume breast surgery practices in San Juan, Puerto Rico. Data collection includes three-generation family cancer history and results from complete BRCA sequencing. A total of six different deleterious mutations were observed, including one mutation in BRCA1 and five mutations in BRCA2. Three recurrent mutations (BRCA1 del exon1-2, BRCA2 4150G>T, and BRCA2 6027del4) account for over 70% of all the BRCA mutations observed in this study population. This study examines for the first time the characteristics of hereditary breast cancer in Puerto Rico and assesses the accuracy of existing genetic risk assessment tools in that population. This data is expected to contribute to providing accurate and efficient tools for the clinical management of hereditary breast cancer in Puerto Rico.

Prevalence of BRCA1 and BRCA2 mutations in unselected breast cancer patients from Greece

BACKGROUND

Inheritance of a mutation in either BRCA1 or BRCA2 accounts for approximately 5% of all breast cancer cases, but varies by country. Investigations into the contribution of BRCA mutations to breast cancer incidence in Greece have been, for the most part, limited by small sample sizes and by the use of cases selected for their family history of cancer. The aim of the current study was to estimate BRCA mutation frequencies in breast cancer patients unselected for family history.

METHODS

To do so, we enrolled 127 unselected women with breast cancer from the Alexandra Hospital in Athens, Greece, a large public hospital in the city. Mutations in BRCA1 and BRCA2 were detected using a combination of techniques and were confirmed by direct sequencing. Two large genomic deletions were sought using mutation-specific assays. A detailed family history of cancer was obtained from each patient.

RESULTS

We were able to successfully complete testing on samples from 127 women. Among these, six mutations were identified (four in BRCA1 and two in BRCA2) representing 4.7% of the total or 9.5% of cases diagnosed before age forty. None of the mutation carriers had a family history of breast or ovarian cancer. Three of the four BRCA1 mutations were in exon 20: two were a G5331A mutation and the third was a 3.2 kb deletion. The fourth BRCA1 mutation was the 3819delGTAAA in exon 11. The two BRCA2 mutations were in exon 11 (3782del10 and 4512insT).

CONCLUSIONS

The G5331A mutation in BRCA1 appears to be a founder mutation in the Greek population.

BRCA1 and BRCA2 mutations among ovarian cancer patients from Colombia

OBJECTIVE

The contribution of BRCA1 and BRCA2 mutations to ovarian cancer in Colombia has not yet been explored. Five founder mutations have been identified in two previous studies of breast cancer patients in the Bogota region [1,2]. It is important that the frequency of mutations be established among unselected cases of ovarian cancer in order to estimate the genetic burden of this cancer in Colombia and to plan genetic and preventive services.

METHODS

We enrolled 100 unselected women with ovarian cancer from the Bogota region, and from northern and southern central regions of Colombia. A detailed family history was obtained from each patient and a blood sample was processed for DNA analysis. DNA quality was adequate for BRCA testing for 96 women. Mutations in BRCA1 and BRCA2 were sought using a Hispanic BRCA mutation testing panel. All mutations were confirmed by direct sequencing.

RESULTS

Fifteen mutations were identified (two in BRCA2 and thirteen in BRCA1) representing 15.6% of the total (95% CI: 7.8% to 21.3%). Among the 15 mutation-positive families there were nine breast-ovarian cancer families, one gastric cancer family, one prostate cancer family, three uterine cancer families, and one family with no history of cancer. A single founder mutation in BRCA1 (3450del4) was seen in 11 patients.

CONCLUSION

In summary, BRCA1 founder mutations are common in Colombian women with ovarian cancer. Approximately 11.5% of all ovarian cancer cases in the Bogota region are attributable to a single BRCA1 founder mutation.

Hereditary ovarian cancer: biology, response to chemotherapy and prognosis

Recent evidence has indicated that the prognosis of women with epithelial ovarian cancer who are BRCA-mutation carriers may be better than for noncarriers. Part of the explanation is a higher sensitivity to platinum and other chemotherapies, as was demonstrated in in vitro studies, as well as a possible different biology. BRCA genes are important in double-strand DNA break repair and in other important processes of the cell cycle. Mutation or reduced activity of BRCA genes leads to a higher vulnerability to DNA damage (caused by chemotherapy and radiotherapy) compared with malignant tumors of noncarriers. New targeted drugs, such as poly (ADP-ribose) polymerase-1 and -2 inhibitors, are currently under investigation, as are new biomarkers that will hopefully lead the way to better treatment and longer survival. Testing for the BRCA mutation should be carried out and used as a guide for therapy in most patients with epithelial ovarian cancer.

Spectrum of BRCA1/2 point mutations and genomic rearrangements in high-risk breast/ovarian cancer Chilean families

The distribution of BRCA1/2 germline mutations in breast/ovarian cancer (BC/OC) families varies among different populations. In the Chilean population, there are only two reports of mutation analysis of BRCA1/2, and these included a low number of BC and/or OC patients. Moreover, the prevalence of BRCA1/2 genomic rearrangements in Chilean and in other South American populations is unknown. In this article, we present the mutation-detection data corresponding to a set of 326 high-risk families analyzed by conformation-sensitive gel electrophoresis and heteroduplex analysis. To determine the contribution of BRCA1/2 LGRs in Chilean BC patients, we analyzed 56 high-risk subjects with no pathogenic BRCA1/2 point mutations. Germline BRCA1/2 point mutations were found in 23 (7.1%) of the 326 Chilean families. Families which had at least three BC and/or OC cases showed the highest frequency of mutations (15.9%). We identified 14 point pathogenic mutations. Three recurrent mutations in BRCA1 (c.187_188delAG, c.2605_2606delTT, and c.3450_3453delCAAG) and three in BRCA2 (c.4969_4970insTG, c.5374_5377delTATG, and c.6503_6504delTT) contributed to 63.6 and 66.7% of all the deleterious mutations of each gene, which may reflect the presence of region-specific founder effects. Taken together BRCA1/2 recurrent point mutations account for 65.2% (15/23) of the BRCA1/2 (+) families. No large deletions or duplications involving BRCA1/2 were identified in a subgroup of 56 index cases negative for BRCA1/2 point mutations. Our study, which is the largest conducted to date in a South American population, provides a comprehensive analysis on the type and distribution of BRCA1/2 mutations and allelic variants.

The contribution of founder mutations to early-onset breast cancer in French-Canadian women

In an ethnically-homogeneous population, it is valuable to identify founder mutations in cancer-predisposing genes. Founder mutations have been found in four breast-cancer-predisposing genes in French-Canadian breast cancer families. The frequencies of the mutant alleles have been measured neither in a large series of unselected breast cancer patients from Quebec, nor in healthy controls. These estimates are necessary to measure their contribution to the hereditary burden of breast cancer in Quebec and to help develop genetic screening policies which are appropriate for the province. We studied 564 French-Canadian women with early-onset invasive breast cancer who were treated at a single Montreal hospital. Patients had been diagnosed at age 50 or less, and were ascertained between 2004 and 2008. We screened all 564 patients for nine founder mutations: four in BRCA1, three in BRCA2 and one each in PALB2 and CHEK2. We also studied 6433 DNA samples from newborn infants from the Quebec City area to estimate the frequency of the nine variant alleles in the French-Canadian population. We identified a mutation in 36 of the 564 breast cancer cases (6.4%) and in 35 of 6443 controls (0.5%). In the breast cancer patients, the majority of mutations were in BRCA2 (54%). However, in the general population (newborn infants), the majority of mutations were in CHEK2 (54%). The odds ratio for breast cancer to age 50, given a BRCA1 mutation, was 10.1 (95% CI: 3.7-28) and given a BRCA2 mutation was 29.5 (95% CI: 12.9-67). The odds ratio for breast cancer to age 50, given a CHEK2 mutation, was 3.6 (95% CI: 1.4-9.1). One-half of the women with a mutation had a first- or second-degree relative diagnosed with breast or ovarian cancer. Thus, it can be concluded that a predisposing mutation in BRCA1, BRCA2, CHEK2 or PALB2 is present in approximately 6% of French-Canadian women with early-onset breast cancer. It is reasonable to offer screening for founder mutations to all French-Canadian women with breast cancer before age 50. The frequency of these mutations in the general population (0.5%) is too low to advocate population-based screening.

BRCA1 5272-1G>A and BRCA2 5374delTATG are founder mutations of high relevance for genetic counselling in breast/ovarian cancer families of Spanish origin

The distribution of BRCA1 and BRCA2 germ line mutations in breast/ovarian cancer families varies among different populations, which typically present a wide spectrum of unique mutations. Splicing mutation 5272-1G>A of BRCA1 and frameshift mutation 5374delTATG of BRCA2 are highly prevalent mutations in Castilla-León (Spain), accounting for 18.4% and 13.6% of BRCA1 and BRCA2 positive families, respectively. To test the presence of founder effects, 9 Spanish 5272-1G>A and 13 5374delTATG families were genotyped with polymorphic markers linked to BRCA1 or BRCA2. All the 5272-1G>A families shared a common haplotype in eight markers (1.1 Mb region) and the mutation age was estimated in 15 generations (approximately 380 years). A conserved haplotype associated to 5374delTATG was observed in four markers (0.82 Mb). The mutation occurred approximately 48 generations ago (approximately 1200 years). Each mutation likely arose from a common ancestor that could be traced to a small area of Castilla-León and expanded to other Spanish regions. They can have a significant impact on the clinical management of asymptomatic carriers as well as on the genetic screening strategy to be followed in populations with Spanish ancestries.